Analog Devices Inc./Maxim Integrated

The LTC4257 provides complete signature and power interface functions for a device operating in an IEEE 802.3af Power over Ethernet (PoE) system. The LTC4257 simplifies Powered Device (PD) design by incorporating the 25k signature resistor, the classification current source, input current limit with thermal foldback, undervoltage lockout and power good signaling, all in a single 8-pin package. By incorporating a high voltage power MOSFET onboard, the LTC4257 provides the system designer with reduced cost while also saving board space.The LTC4257 can interface directly with a variety of ADI's DC/DC converter products to provide a cost effective power solution for IP phones, wireless access points and other PDs. Analog Devices also provides solutions for Power Sourcing Equipment (PSE) applications with quad network power controllers.The LTC4257 is available in the 8-pin SO and low profile (3mm × 3mm) DFN packages.ApplicationsIP Phone Power ManagementWireless Access PointsTelecom Power Control

The LTC4257-1 provides complete signature and power interface functions for a device operating in an IEEE 802.3af Power over Ethernet (PoE) system. The LTC4257-1 simplifies Powered Device (PD) design by incorporating the 25k signature resistor, classification current source, input current limit, undervoltage lockout, thermal overload protection, signature disable and power good signalling, all in a single 8-pin package. The LTC4257-1 includes a precision, dual level current limit circuit. This allows it to charge large load capacitors and interface with legacy Power over Ethernet systems while maintaining compatibility with the current IEEE 802.3af specification. By incorporating a high voltage power MOSFET onboard, the LTC4257-1 provides the system designer with reduced cost while also saving board space.The LTC4257-1 can interface directly with a variety of ADI DC/DC converter products to provide a cost effective power solution for IP phones, wireless access points and other PDs. Analog Devices also provides network power controllers for Power Sourcing Equipment (PSE) applications.The LTC4257-1 is available in the 8-pin SO and low profile (3mm x 3mm) DFN packages.ApplicationsIP Phone Power ManagementWireless Access PointsTelecom Power Control

The LTC4258 is a quad –48V Hot Swap™controller designed for use in IEEE 802.3af compliant Power Sourcing Equipment (PSE). It consists of four independent ports, each with output current limit, short-circuit protection, complete Powered Device (PD) detection and classification capability, and programmable PD disconnect using DC sensing. Used with power MOSFETs and passives as in Figure 1, the LTC4258 can implement a complete IEEE 802.3af-compliant PSE.The LTC4258 can operate autonomously or be controlled by an I2C serial interface. Up to 16 LTC4258s may coexist on the same data bus, allowing up to 64 powered Ethernet ports to be controlled with only two digital lines. Fault conditions are optionally signaled with theINTpin to eliminate software polling.External power MOSFETs, current sense resistors and diodes allow easy scaling of current and power dissipation levels and provide protection against voltage and current spikes and ESD events.The LTC4258 is available in a 36-pin SSOP package.Analog Devices also provides solutions for 802.3af PD applications with the LTC4257, LTC4257-1, and LTC4267.ApplicationsIEEE 802.3af Compliant Endpoint and Midspan Power SourcesIP Phone SystemsDTE Power Distribution

The LTC4259A is a quad –48V Hot Swap™controller designed for use in IEEE 802.3af compliant Power Sourcing Equipment (PSE). It consists of four independent ports, each with output current limit, short-circuit protection, complete Powered Device (PD) detection and classification capability, and programmable PD disconnect using AC or DC sensing. Used with power MOSFETs and passives as in Figure 1, the LTC4259A can implement a complete IEEE 802.3af-compliant PSE.The LTC4259A can operate autonomously or be controlled by an I2C serial interface. Up to 16 LTC4259As may coexist on the same data bus, allowing up to 64 powered Ethernet ports to be controlled with only two digital lines. Fault conditions are optionally signaled with theINTpin to eliminate software polling.External power MOSFETs, current sense resistors and diodes allow easy scaling of current and power dissipation levels and provide protection against voltage and current spikes and ESD events.The LTC4259A is available in a 36-pin SSOP package.Analog Devices also provides solutions for 802.3af PD applications with the LTC4257, LTC4257-1 and LTC4267.ApplicationsIEEE 802.3af Compliant Endpoint and Midspan Power SourcesIP Phone SystemsDTE Power Distribution

The LTC4263 is an autonomous single-channel PSE controller for use in IEEE 802.3af compliant Power over Ethernet systems. It includes an on-board power MOSFET, internal inrush, current limit, and short-circuit control, IEEE 802.3af compliant PD detection and classification circuitry, and selectable AC or DC disconnect sensing. On-board control algorithms provide complete IEEE 802.3af compliant operation without the need of a microcontroller. The LTC4263 simplifies PSE implementation, needing only a single 48V supply and a small number of passive support components.Programmable on-board power management circuitry permits multiple LTC4263s to allocate and share power in multi-port systems, allowing maximum utilization of the 48V power supply—all without the intervention of a host processor. The port current limit can be configured to automatically adjust to the detected PD class. Detection back-off timing is configurable for either Endpoint or Midspan operation. Built-in foldback and thermal protection provide comprehensive fault protection.An LED pin indicates the state of the port controlled by the LTC4263. When run from a single 48V supply, the LED pin can operate as a simple switching current source to reduce power dissipation in the LED drive circuitry.The LTC4263 is available in 14-pin 4mm × 3mm DFN and 14-pin SO packages.ApplicationsIEEE 802.3af Compliant Endpoint/Midspan PSEsSingle-Port or Multi-Port Power InjectorsPower ForwardersLow-Port Count PSEsEnvironment B PSEsStandalone PSEs

The LTC4263-1 is a high power, single PSE controller for use in Power over Ethernet systems. The internal current limit and short-circuit protection are designed to provide up to 30W of PSE output power for power hungry PoE applications such as WAPs, security cameras and RFID readers.The LTC4263-1 includes IEEE 802.3af compliant PD detection circuitry along with selectable AC and DC disconnect sensing, allowing seamless operation in conventional IEEE 802.3af systems as well as propriety, high power applications. The LTC4263-1 simplifi es PSE implementation, needing only a single supply and a small number of passive support components. Onboard control algorithms provide complete PSE functionality without the need of a microcontroller and built-in foldback and thermal shutdown provide comprehensive fault protection. An LED pin indicates the state of the port and detection backoff timing is confi gurable for either endpoint or midspan operation.The LTC4263-1 is available in a miniature 14-pin 4mm × 3mm DFN package.ApplicationsHigh Power Endpoint/Midspan PSEsSingle-Port or Multi-Port Power InjectorsLow Port Count PSEsEnvironment B PSEsStandalone PSEs